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EPA cuts Nogales some slack on air quality because of cross-border pollution

The Air Quality Flag Program uses nautical-style flags, based on the Environmental Protection Agency’s Air Quality Index, to notify the public of air quality conditions.

Green flagAir quality is good and you do not need to change your outdoor activities.

Yellow flag Air quality is acceptable, but there might be health concerns for some people.

Orange flag Pollution levels may be unhealthy for sensitive groups.

Red flag Air quality is unhealthy and everybody may begin to feel some health effects.

Source: Arizona Department of Environmental Quality

WASHINGTON – The U.S. Environmental Protection Agency this week agreed with Arizona that the city of Nogales would be in compliance with clean-air standards – if it wasn’t for pollution drifting over from Mexico.

The statement came as part of EPA’s approval of an Arizona Department of Environmental Quality plan to help Nogales meet U.S. air-quality standards. That notice was published Tuesday in the Federal Register.

The notice says, among other things, that EPA reviewed three years of air-quality data from the state and determined that the majority of emissions recorded in Nogales, Ariz., were coming from Nogales, Sonora, Mexico.

“On the Arizona side, they’re below the standard” for pollutants, said Colleen McKaughan, an associate director in the air division at EPA Region 9 in San Francisco. But pollution, dust and smoke from Mexico pushes the U.S. city back over the standard, she said.

Over 90 percent of the pollution in Nogales, Ariz. comes from Mexico, said ADEQ spokesman Mark Shaffer. He said that’s because there is a “downhill slope from Mexico into Arizona.”

Because Nogales, Ariz., exceeds U.S. pollution standards, the state has to submit a proposal to the EPA outlining what it has done and what it plans to do to meet the standard, McKaughan said.

The plan approved by the EPA recognizes that Nogales will not always be in compliance because of its sister city to the south. McKaughan said that under the State Implementation Plan published this week, Arizona also outlined proposals to help reduce the flow of dust by paving dirt roads and to cut vehicle emissions by speeding border crossings, so cars are not sitting and idling for too long.

The cooperation commission and the development bank work together to pave dirt roads in cities on both sides of the border, said Irma Flores, a spokeswoman for the commission.

The two organizations strive “to enhance the environmental conditions along the U.S. and Mexican border to benefit residents in both nations,” she said.

In addition to the plan submitted to the EPA, the state has also installed a monitor on top of the Nogales, Ariz., post office that will help forecast the region’s air quality every day. The air quality will be passed on to the public through color-coded alerts, Shaffer said.

The new system will help residents, city and school officials avoid scheduling outdoor activities during times when high dust pollution is predicted.

Shaffer said he hopes the new system will help the area come back into compliance with EPA standards.

McKaughan said it “might definitely help” the city meet EPA standards because people would be more aware of when pollution is high and might be spurred to take actions that would ease the situation.

The U.S.-Mexico border fence, running from upper left to lower right in this 2004 aerial photograph, divides Nogales, Ariz., on the left and Nogales, Sonora, on the right.

Photo by Pamela L. Nagler, U.S. Geological Survey

The sister cities of Nogales, Ariz., and Nogales, Sonora, Mexico, form one of the busiest trucking ports on the U.S.-Mexico border.